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Comparison of element abundance between the exposed crust of the continent of China and the global averaged upper continental crust: Constraints on crustal evolution and some speculations
被引:2
|作者:
Wang Y.
[1
,2
]
机构:
[1] School of Earth Sciences and Resources, China University of Geosciences
[2] Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences
来源:
基金:
中国国家自然科学基金;
关键词:
Continent of China;
Element abundance;
Exposed crust;
Geochemistry;
D O I:
10.1007/s11707-007-0010-9
中图分类号:
学科分类号:
摘要:
Based on the results of a study of regional element abundance in eastern China and the 1:200 000 geochemical surveys in northern Xinjiang, the element geochemical characteristics of the exposed crust in 23 tectonic units of the continent of China are summarized. Compared with the global average abundance of the upper continental crust, the exposed crust of the continent of China is compositionally more evolved than the upper crust of the island arc, but less evolved than the mature Precambrian Canadian shield. The exposed crust of the North China and Yangtze platforms has a lower SiO2 content, but markedly higher CaO and MgO contents due to the presence of widespread carbonate strata, which suggests that we should not neglect the contribution of carbonate rocks in the study of the exposed crust and the element abundance of the upper crust. In comparison with two recently published average compositional models of the global upper continental crust, the exposed crust of the continent of China is depleted in Au, Hg, Mo, Sn, and W, which suggests that their abundance in the present global models is overestimated. The exposed crust of the North China platform and the Qinling-Dabieshan fold belt to its south has lower μ(238U/ 204Pb) values (<8), but other regions of the continent of China exhibit much higher μ values, which implies that the low μ feature of the North China platform and its adjacent regions does not have global significance. Considering the apparent lateral variation in composition of the exposed crust for the tectonic units of the continent of China, there is no adequate reason to take the average upper crust compositional model of the North China platform and its adjacent regions as a reliable composition representative for Chinese and global upper continental crust composition. © Higher Education Press and Springer-Verlag 2007.
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页码:69 / 79
页数:10
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